There are several types of magnetometers currently being used. The least expensive and least sensitive devices with resolution of about 10.sup.-1 Oersted (Oe)/Hz.sup.1/2 are Hall probe devices. These devices work by sensing a voltage change across a conductor placed in a magnetic field. Such devices are insensitive and so can not be used in applications requiring greater sensitivity such as required in brain scan devices and magnetic anomaly detection devices.
Flux gate magnetometers are more sensitive, having resolution of approximately 10.sup.-6 Oe/Hz.sup.1/2. Flux gate magnetometers employ a magnetic core surrounded by an electromagnetic coil, and so are difficult to microfabricate. Additionally, flux gate magnetometers require a relatively large amount of power and accordingly do not lend themselves to a compact, portable design.
The most sensitive magnetometers called SQUIDS (superconducting quantum interference detectors) have a resolution of about 10.sup.-10 Oe/Hz.sup.1/2. However, because they include a superconducting element these devices must have provision for cooling to liquid gas temperatures, making them extremely bulky and expensive to operate. Their size limits their utility because the active superconducting element can not be placed directly adjacent to the source of the magnetic field, for example the brain.
Accordingly, there is a great need for a small, inexpensive, low power magnetometer that has sufficient sensitivity to be useful for a variety of magnetometer applications.